Eccentric cycling, where the goal is to resist the pedals, which are driven by a motor, increases muscle strength and size in untrained subjects. We hypothesized that it could also be beneficial for athletes, particularly in alpine skiing, which involves predominantly eccentric contractions at longer muscle lengths. We investigated the effects of replacing part of regular weight training with eccentric cycling in junior male alpine skiers using a matched-pair design. Control subjects ( N=7) executed 1-h weight sessions 3 times per week, which included 4-5 sets of 4 leg exercises. The eccentric group ( N=8) performed only 3 sets, followed by continuous sessions on the eccentric ergometer for the remaining 20 min. After 6 weeks, lean thigh mass increased significantly only in the eccentric group. There was a groupxtime effect on squat-jump height favouring the eccentric group, which also experienced a 6.5% improvement in countermovement-jump height. The ability to finely modulate muscle force during variable eccentric cycling improved 50% (p=0.004) only in the eccentric group. Although eccentric cycling did not significantly enhance isometric leg strength, we believe it is beneficial for alpine skiers because it provides an efficient means for hypertrophy while closely mimicking the type of muscle actions encountered while skiing.

Non-circular chainrings theoretically enhance cycling performance by increasing effective chainring diameter and varying crank velocity, but research has failed to consistently reproduce the benefits in cycling trials. The aim of this study was (1) to investigate the effect of different chainring shapes on sagittal knee joint moment and sagittal lower limb joint powers and (2) to investigate whether alterations are affected by cadence and workload. Fourteen elite cyclists cycled in six conditions (70, 90 and 110 rpm, each at 180 and 300 W), for 2 min each, using three chainrings of different ovalities (1.0-1.215). Kinematic data and pedal forces were collected. For most conditions, only the chainring with the highest ovality (1.215) was characterised by smaller sagittal knee joint moments, smaller relative sagittal knee joint power contribution and larger relative sagittal hip joint power contribution, which suggests a change from maximising efficiency to maximising power production. Effect sizes increased with higher cadences, but not with higher workload. This study has application for athletes, clinicians and sports equipment industry as a non-circular chainring can change joint-specific power generation and decrease knee joint moment, but certain ovality seems to be necessary to provoke this effect.

No abstract

Introduction: Functional characteristics of prosthetic ankle design may facilitate sloped walking for transfemoral amputees. The aim of the current case-study was to analyse the effects of a rigid vs. a hydraulically articulating ankle component on the biological joint moments of a transfemoral amputee during downhill, uphill and level walking. Methods: The gait of one unilateral transfemoral amputee, using the same prosthetic foot with rigid and hydraulic ankle components, was analysed and compared to a control group of 18 able-bodied participants. Kinematic and kinetic data were recorded at self-selected walking speed on a sloped ramp with inclinations of-12°,-4° (downhill), 0° (level), +4° and +12° (uphill). Results: The slope influenced lower limb joint moments similarly in both able-bodied and transfemoral participants. The effect of altering ankle movement through exchanging prosthetic ankle componentry was most acutely seen at the hip joint of the residual limb. The use of a hydraulic ankle joint component resulted in decreased mean hip joint extension and flexion moments of up to 92% and 48% respectively in the residual limb when compared to using the rigid ankle joint component, respectively. Conclusion: During sloped walking, the use of a hydraulically articulating vs. rigid ankle joint component reduced the joint moments observed at the hip joint of the residual limb in a unilateral transfemoral amputee. This indicates a benefit for transfemoral amputees as the increased ankle function reduces the moment producing requirements of the hip joint which may result in decreased energy consumption and subsequently, a more efficient gait.

No abstract